In recent years, advances in technology, as well as ever evolving tastes in style, have led to substantial changes in the design of automobiles. One of the changes involves the power usage and complexity of the various electrical systems within automobiles, particularly alternative fuel vehicles, such as hybrid, electric, and fuel cell vehicles.
Many of the electrical components, including the electric motors used in such vehicles, receive electrical power from alternating current (AC) power supplies. However, the power sources (e.g., batteries) used in such applications provide only direct current (DC) power. Thus, devices known as “power inverters” are used to convert the DC power to AC power, which often utilize several of switches, or transistors, operated at various intervals to convert the DC power to AC power.
Additionally, such vehicles, particularly fuel cell vehicles, often use two separate voltage sources (e.g., a battery and a fuel cell) to power the electric motors that drive the wheels. “Power converters,” such as direct current-to-direct current (DC/DC) converters, are typically used to manage and transfer the power from the two voltage sources. Modern DC/DC converters often include transistors electrically interconnected by an inductor. By controlling the states of the various transistors, a desired average current can be impressed through the inductor and thus control the power flow between the two voltage sources.
The utilization of both a power inverter and a power converter greatly increases the complexity of the electrical system of the automobile. The additional components required for both types of devices also increase the overall cost and weight of the vehicle. Accordingly, systems and methods have been developed for operating a motor coupled to multiple power sources without a DC/DC converter while maximizing the performance of the motor by utilizing dual inverter electrical systems.
Traditional automotive systems include electrical systems designed for three-phase motors. However, multi-phase motor drives with more than three phases operate with improved efficiency and reduce the required inverter per-phase power rating. In some cases, this may result in cheaper and more compact power inverters in addition to improved motor performance. Additionally, multi-phase motor drives with at least five or more phases may be configured in series in an appropriate manner with another motor drive, thereby reducing the number of power inverters required in a system while providing independent control of both motors.
Accordingly, it is desirable to provide systems and methods for operating a series-coupled two-motor drive using a dual inverter system coupled to two separate energy sources. Other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background